Hyperthyroidism Diagnosis
Diagnosis
Thyroid storm or thyroid crisis
- An acute life-threatening exacerbation of hyperthyroidism
- Signs & symptoms include high fever, changes in sensorium, restlessness, severe tachycardia & arrhythmia
- May be precipitated by trauma, infection, dehydration
History
- A comprehensive history should be elicited
- Combination of ophthalmopathy & hyperthyroidism is suggestive of Graves’ disease
- Most patients have (positive) family history of autoimmune thyroid disease
Physical Examination
- Weight, height, & blood pressure (BP)
- Heart rate (HR), cardiac rhythm, & respiratory rate (RR)
- Inspect & auscultate the neck (check size, nodule, texture of goiter; thyroid bruit)
- Ocular & lymphatic examination
- Combination of ophthalmopathy & hyperthyroidism is suggestive of Graves’ disease
- Dermatological examination (eg excessive sweating, onycholysis, vitiligo, alopecia)
- Neurologic exam: Presence of tremors, proximal muscle weakness
Laboratory Tests
- Obtain baseline CBC which includes WBC count with differential, and liver profile (ie serum alanine aminotrasferase, aspartate aminotransferase, gamma glutamyl transpeptidase, bilirubin)
- Recommended as initial diagnostic exam for patients suspected to have hyperthyroidism
- Serum TSH measurement is highly sensitive & specific for the evaluation of hyperthyroidism
- TSH levels are decreased in patients w/ hyperthyroidism
- TSH receptor stimulating autoantibodies titers are elevated in Graves’ disease w/ 95% sensitivity & 96% specificity
- Not routinely measured
Thyroxine (T4) Levels
- Measure both total & free serum T4 levels
- Free T4 improves diagnostic sensitivity/specificity when combined w/ measured TSH levels
Triiodothyronine (T3) Levels
- Measure both total & free T3 levels; total T3 measurement preferred for diagnostic purposes
- T3 levels may be more elevated than T4
Others
- T4 binding globulin (TBG), transthyretin (TTR)
Imaging
Ultrasound
- Useful in evaluating the size & shape of the thyroid, especially in large glands
Radioactive Iodine Uptake (RAIU) Test
- Recommended to determine the cause of hyperthyroidism
- Usually normal or elevated in the following: Graves disease, toxic adenoma, toxic multinodular goiter, trophoblastic disease, TSH-producing pituitary adenoma, T3 receptor mutation
- Near-absent uptake with RAIU usually seen in the following: Silent thyroiditis, Amiodarone-induced thyroiditis, de Quervain’s thyroiditis, iatrogenic thyrotoxicosis, struma ovarii
Thyroid Scan
- Recommended for patients with presence of thyroid nodularity
Disease Severity
Overt Hyperthyroidism
- Increased T3, T4 levels, subnormal/undetectable TSH
- Adrenergic manifestations are often more pronounced (eg tachycardia, anxiety, tremor)
Subclinical Hyperthyroidism
- Normal T3, T4 levels, low/undetectable serum TSH
- Milder form of hyperthyroidism